1. Field Of The Invention
This invention relates to a gas sensor operating system in closed loop fuel injection systems and, more particularly, to control systems responding to particular engine operating conditions requiring a fixed predetermined air/fuel ratio.
2. Prior Art
The basic closed loop control fuel injection system for motor vehicles having internal combustion engines utilizes an oxygen gas sensor responding to the amount of oxygen present in the exhaust gas for modifying the air/fuel ratio. The limitations on the use of the presently known sensors is that at cold start conditions the sensor, an electrochemical device, being cold has a high internal impedance and is therefore unable to function properly.
In order to avoid the misinformation which is developed by a cold sensor, some prior art closed loop systems provide several time delays that are activated upon actuation of the ignition to start the engine. The time selected for the time delay is generally that relating to "worst case" conditions. Thus, for each cold start condition, whether or not the actual temperature conditions warrant it, the time delay operates for the same, generally long, time. This results in an engine operation which may not be the most desirable in terms of economy and emission.
A. L. Oberstadt, in his co-pending patent application Ser. No. 510,276 U.S. Pat. No. 3,938,479 entitled "Exhaust Gas Sensor Operating Temperature Detection System" provides a system for generating an electrical control signal whenever the temperature of the sensor exceeds a predetermined level. However, in the complete control of a closed loop fuel injection system, other engine operating parameters must be considered which indicate that the engine and fuel management system are in condition for best operation.